European Journal of Cardiovascular Medicine

The placenta plays a critical role in the development of the fetus during pregnancy, acting as a lifeline that supplies oxygen and nutrients, while also removing waste products. The assessment of placental morphology, including its thickness, has emerged as a pivotal component in prenatal ultrasonography, offering insights into placental function and potential implications for fetal health. The study of placental thickness at specific gestational milestones, particularly at the 32nd and 36th weeks, holds promise for predicting fetal outcomes, thereby guiding clinical decision-making and interventions to optimize maternal and neonatal health.

Placental thickness mirrors placental function and is influenced by various physiological and pathological conditions. Physiologically, the placenta grows in thickness to accommodate the increasing demands of the growing fetus. However, deviations from the normal range of placental thickness can indicate pathological conditions that may affect the fetus's development and outcome. Excessive placental thickness, for instance, is associated with conditions like gestational diabetes mellitus and placental chorioangioma, which can lead to complications such as fetal macrosomia and polyhydramnios, respectively[^1],[^2]. Conversely, insufficient placental thickness may suggest placental insufficiency, potentially leading to intrauterine growth restriction (IUGR) and adverse neonatal outcomes[^3].

The correlation between placental thickness measured via ultrasound at the 32nd and 36th weeks of gestation and fetal outcomes has garnered attention in recent research. These gestational weeks are critical in fetal development, with significant growth and maturation processes occurring. By assessing placental thickness at these stages, researchers aim to identify early signs of potential complications, facilitating timely interventions. Studies have demonstrated that abnormal placental thickness measurements during this period can be indicative of adverse outcomes, including preterm birth, low birth weight, and the need for neonatal intensive care unit (NICU) admission[^4],[^5].

The objectives of the proposed study are twofold: first, to establish a correlation between placental thickness measurements at the 32nd and 36th weeks of gestation and fetal outcomes; and second, to evaluate the predictive value of these measurements for identifying pregnancies at risk of adverse outcomes. This research is anticipated to contribute valuable data to the field, supporting the development of guidelines for the monitoring and management of pregnancies based on placental thickness measurements.

Aims and Objectives

The primary aim of this observational study was to establish a correlation between placental thickness measured at the 32nd and 36th weeks of gestation and the fetal outcomes in singleton pregnancies. This research sought to understand better how variations in placental thickness during these specific gestational ages could predict outcomes such as APGAR scores, birth weight, and the necessity for neonatal intensive care unit (NICU) admission, thereby aiding in the early identification of at-risk pregnancies.

The study was designed as an observational study, meticulously planned and executed to ensure a comprehensive examination of the correlation between placental thickness at significant gestational milestones and fetal outcomes.

Study Setting and Period

The observational study was conducted at PES Institute of Medical Sciences and Research (PESIMSR), with the study period spanning from January 2019 to March 2020. This timeframe allowed for a detailed and extensive collection of data across different seasons and conditions, ensuring a robust dataset for analysis.

Study Population

The study population consisted of all singleton pregnant women who attended regular antenatal visits at the study setting during the study period. A convenience sampling method was employed to select the participants, focusing on those who met the specified inclusion criteria.

Sampling Method and Sample Size

Using convenience sampling, a total of 112 participants were included in the study. This sample size was determined based on the formula suited for observational studies, ensuring statistical significance and reliability of the findings.

Inclusion and Exclusion Criteria

The inclusion criteria were strictly adhered to, with only singleton pregnant women aged between 18-40 years being considered for the study. This criterion was chosen to focus on a population with the least number of confounding variables. Women with medical and obstetric high-risk factors, including diabetes mellitus, hypertension, chronic renal disease, multiple pregnancies, and a low-lying placenta, were excluded from the study. Additionally, patients who were not willing to provide informed consent were also excluded, ensuring that all participants were fully informed and agreeable to their involvement.

Tools for the Study

Several tools were utilized for data collection, including informed consent forms, patient detail forms, ultrasound reports with placental thickness measurements, APGAR scores, birth weight records, and NICU admission and duration details. These tools were crucial in gathering comprehensive data for each study subject.

Procedure for Data Collection

Data collection was meticulously carried out after obtaining informed consent from each participant. A separate proforma was used for every study subject, ensuring that all necessary information was captured accurately and consistently. The data collection process was promptly concluded after the delivery of each participating woman, ensuring that the most relevant and immediate data were gathered for analysis.

Statistical Analysis

The collected data were entered into MS Excel 2007 for initial organization and then analyzed using SPSS version 20. Descriptive analysis was conducted to understand the distribution of categorical variables, which were analyzed using percentages. Continuous variables, on the other hand, were analyzed by calculating the mean ± Standard Deviation, providing a clear overview of the data trends and any significant correlations between placental thickness at the specified gestational weeks and fetal outcomes.

The results of this observational study on the correlation between placental thickness at the 32nd and 36th weeks of gestation and fetal outcomes reveal significant findings that contribute to the understanding of placental thickness as a predictive measure for fetal health.

In the study population of 112 participants, a significant majority (91.07%) were aged between 19 to 30 years, with a smaller representation from the less than 19 years (3.57%) and more than 30 years (5.35%) age groups. Most of the study subjects were term deliveries, with 95.5% of births occurring at 37 weeks gestation or later, indicating a predominance of full-term pregnancies in the study sample.

Analysis of placental thickness and its association with neonatal intensive care unit (NICU) stay revealed distinct patterns. At 32 weeks of gestation, 43.3% of subjects with a placental thickness of less than 3.01 cm required NICU admission, compared to only 1.7% in the 3.01-3.67 cm group and 60% in the greater than 3.67 cm group. Similarly, at 36 weeks, the need for NICU care was significantly higher among newborns with placentas measuring less than 3.01 cm (64.7%) and more than 3.67 cm (26.3%), compared to those within the 3.01-3.67 cm range (5.9%).

The study further explored the relationship between placental thickness and birth weight. For placentas measured at 32 weeks, a significant proportion of newborns with a placental thickness of less than 3.01 cm had a birth weight of less than 2.5 kg (40%), contrasting with 10.5% and 20% in the 3.01-3.67 cm and greater than 3.67 cm groups, respectively. This pattern was consistent at 36 weeks, where 64.7% of newborns with a placenta measuring less than 3.01 cm fell into the lower birth weight category, as opposed to 11.7% and 13.1% in the other two groups.

Furthermore, the study examined the association between placental thickness and APGAR scores at 1 minute post-delivery. At 32 weeks, newborns with a placental thickness of less than 3.01 cm and more than 3.67 cm exhibited a higher incidence of APGAR scores less than 4, at 23.3% and 32.0%, respectively, with no cases reported in the 3.01-3.67 cm group. This trend was echoed at 36 weeks, underscoring the potential impact of placental thickness on immediate neonatal health status.

Placental weight in grams also correlated with its thickness at both 32 and 36 weeks. Notably, at 32 weeks, the groups with placental thickness of less than 3.01 cm and more than 3.67 cm presented a higher variance in placental weight, suggesting a potential link between placental thickness and overall placental weight, which could have implications for fetal nutrient transfer and growth.

The statistical analysis, including chi-square values and p-values, provided robust support for the observed associations. For example, the association between placental thickness at 32 weeks and birth weight less than 2.5 kg yielded a chi-square value of 10.4688 with a significant p-value of 0.005, indicating a strong correlation. Similarly, the relationship between placental thickness at 36 weeks and APGAR scores less than 4 was statistically significant, with a chi-square value of 10.2362 and a p-value of 0.006.

In conclusion, this study demonstrates a significant correlation between placental thickness measured at the 32nd and 36th weeks of gestation and key fetal outcomes, including NICU stay, birth weight, and APGAR scores. These findings underscore the potential of placental thickness as a valuable predictive marker for identifying pregnancies at risk of adverse outcomes, thereby enabling targeted interventions to improve neonatal health.

The findings from the current study illuminate the significant relationship between placental thickness measured at the 32nd and 36th weeks of gestation and fetal outcomes, including NICU admission rates, birth weights, and APGAR scores. These correlations are critical in the context of prenatal care, offering potential pathways for the early identification and management of at-risk pregnancies.

The increased incidence of NICU stays associated with both lower (<3.01 cm) and higher (>3.67 cm) placental thickness measurements underscores the complex role the placenta plays in fetal development. Placentas with thickness outside the 3.01-3.67 cm range may indicate underlying pathologies or anomalies affecting fetal growth and development, necessitating closer monitoring and, in some cases, early intervention[^6]. This is consistent with prior research indicating that deviations in placental thickness are linked to adverse pregnancy outcomes, including preterm birth and fetal growth restriction[^7],[^8].

The significant relationship between placental thickness and birth weight further supports the placenta's critical role in fetal nutrition and growth. The observed lower birth weights associated with placental thickness at both extremes (<3.01 cm and >3.67 cm) at 32 and 36 weeks gestation align with earlier findings that abnormal placental morphology can predict growth restrictions and lower birth weights[^9]. These findings echo the work of Salafia et al., who noted that placental pathology could be a key predictor of birth weight and overall fetal health[^10].

Moreover, the association between placental thickness and APGAR scores at 1 minute post-birth highlights the potential immediate impact of placental health on neonatal well-being. The increased likelihood of lower APGAR scores in newborns with placentas measuring <3.01 cm or >3.67 cm at 32 and 36 weeks suggests that placental efficiency, reflected in part by its thickness, plays a crucial role in the immediate postnatal adaptation of the newborn[^11]. This supports the hypothesis that placental function, as indicated by its morphology, has a direct impact on neonatal outcomes and survival immediately after birth.

The significant statistical values obtained in this study (chi-square and p-values) provide a robust framework for understanding the predictive value of placental thickness measurements. The correlations established here are in line with the broader body of evidence suggesting that ultrasound measurements of the placenta can serve as important indicators of fetal health and the risk of adverse outcomes[^12].

Limitations

This study, while comprehensive, is not without its limitations, including its single-center design and the inherent challenges of comparing outcomes across different healthcare systems. Future research should focus on multicenter studies and the implementation of standardized plan protocols to enhance the comparability of data. Additional limitations may be related to the increasing rates of preterm deliveries before 36weeks which hinder the proper follow up and the scan should be done by a single radiologist which is of a greater limitation for a proper outcome.

The study comprehensively investigated the correlation between placental thickness at the 32nd and 36th weeks of gestation and fetal outcomes, including NICU admission rates, birth weights, and APGAR scores. The results unequivocally demonstrate that deviations in placental thickness—both below 3.01 cm and above 3.67 cm—are significantly associated with adverse fetal outcomes. Specifically, abnormal placental thickness was correlated with increased NICU admissions, lower birth weights, and reduced APGAR scores at 1 minute post-birth. These findings underscore the pivotal role of placental health in fetal development and highlight the potential of placental thickness measurements as predictive markers for identifying at-risk pregnancies. Early identification through ultrasound assessment could facilitate targeted interventions to improve neonatal health outcomes. The study’s statistical analysis provided robust support for these associations, reinforcing the importance of placental evaluation in prenatal care.

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